Gas lances are used in metallurgical melt vessels, such as converters or ladles, in order to treat the melt contained therein by blowing in gases, e.g. CO2. The streaming gas is supposed in particular to cause turbulence, thus causing a thorough mixing of the melt. The gases flow past the entry surface, which preferably faces the floor of the metallurgical vessel, into the gas lance, and exit at the exit surface. The gas lance is integrated into the fireproof lining of the melt vessel.
The gas lance can on the one hand be made of a porous fireproof material, so that the gas flows through the lance as a whole, thus resulting in a finely distributed flow of gas inside the melt. On the other hand, channels can also be situated in the gas lance via which the gas is distributed in the melt.
From DE 36 25 117 C1, on which the present invention is based, a gas lance is known that is fashioned as a truncated cone and has slit-shaped channels running parallel to the axis of the truncated cone whose cross-sections point radially outward in a star-shaped pattern. In addition, the channels taper towards the exit surface in such a way that the length of the slit-shaped cross-section of the channels decreases.
A disadvantage of a gas lance of this type is that there is the risk there will take place merely a penetration of the gas through the melt column situated over the exit opening. In such a case, there will not be a turbulence of the melt; rather, the melt will remain essentially at rest. The desired mixing effect is then not achieved.